http://www.khanacademy.org/ The Khan Academy is a not-for-profit organization with the mission of providing a high quality education to anyone, anywhere.There are over 1200 videos on YouTube covering everything from basic arithmetic and algebra to differential equations, physics, chemistry, biology and finance.
Teachers' Domain is an extensive library of free digital media resources produced by public television, designed for classroom use and professional development. more information
This NSTA selected site provides numerous links for biology and chemistry activities, labs and demos. http://www.nclark.net/
The Science Channel (with Scandium's symbol) is just a plain fun website with games and puzzles. This site also has some funny interactives -- including a mumbling Isaac Newton. http://science.discovery.com/
Science Curriculum Links